Question

A gas jar containing air is placed upside down on a gas jar of bromine vapour. It is observed that after some time, the gas jar containing air also becomes reddish brown.
i.Explain why this happens.
ii.Name the process involved.

Answer 1

Hint:Gaseous atoms are free to move randomly in the available space. Bromine is a liquid in its standard state.
-Bromine vapours consists of atoms of bromine in gaseous state. the movement of gaseous atoms takes place so as to maintain the equilibrium.

Complete step by step answer:
Bromine vapours consists of bromine atoms. We know the properties of gases. Their atoms move with maximum kinetic energy. Their motion is random and these gaseous molecules collide with one another as well as the walls of the container in which they are placed.
When a gas jar full of air is placed upside down on a gas jar of bromine vapour we see that after some time the gas jar containing air also becomes reddish brown. This is because both air and bromine vapours are gaseous in nature. The atoms from air and bromine vapours start to mix with one another and collide with each other as well as on the walls of the container and bounce back in all directions and because of this they mix uniformly.
 (b)The bromine vapours are transferred from higher concentration regions to regions of lower concentration (the gas jar containing air). Such a phenomenon is called diffusion. In simple words we can say that diffusion is the mixing of two substances with each other. Hence after some time the gas jar containing air also appears reddish brown.

Note:
-Bromine vapours are lighter than air. Bromine vapours are typically amber colored. It has a pungent odour and causes irritation to the skin, eyes. Exposure to such vapours can prove fatal in some cases.
-Other examples of diffusion include the diffusion of oxygen gases in lungs, diffusion of perfume in an entire room.
-Diffusion process is faster in case of gases as compared to solids and liquids. Diffusion is also an important process for living things. By such process ions move in and out of the cell.